What is the purpose of a PDU if not for remote switching?

I just use a 20 amp 2 pole breaker to drive a duplex 20A 250V outlet for each pair of S9s.
I use 12/2 with ground wire cable. It has a yellow jacket conforming to the newest jacket color code. 

All the parts are cheap and readily available from Home Depot, Lowes or ebay.

If you need to add more S9s, just add a sub panel. These are also cheap and off the shelf available.